Flabellicauda alleni, Fujiwara & Conway & Motomura, 2021

Fujiwara, Kyoji, Conway, Kevin W. & Motomura, Hiroyuki, 2021, Description of a New Genus and Two New Species of Indo-Pacific Clingfishes (Gobiesocidae: Diademichthyinae) with Redescription and Reassignment of Two Species Previously Assigned to Lepadichthys Waite, 1904, Ichthyology & Herpetology 109 (3), pp. 753-784 : 757-765

Flabellicauda alleni , new species urn:lsid:zoobank.org:act:894EA26C-06A0-465A-98AA-798063F6B9BA

Allen’s Clingfish

Figures 1A , 2A , 3 , 4A–E , 5 , 6A–C , 7A , 8A–D , 9–15 ; Tables 1–4

Lepadichthys bolini (not of Briggs)— Conway et al., 2018a: 99, fig. 17 (CT-scanned skeleton; Philippines: based on 1 of ROM 55185); Fujiwara and Motomura, 2018: 92, fig. 6 (comparative material; Palau: based on BPBM 9219); Conway et al., 2020: 893, figs. 3, 4 (molecular result; Wainilu, Rinca [Komodo Region], Indonesia: based on WAM P. 34628-002).

Holotype.— USNM 360264 , 26.2 mm SL, west of Cuyo Island , Palawan, Philippines, 10851 0 12 00 N, 121800 0 14 00 E, 0.6–1.2 m, V. Springer et al., 21 May 1978.

Paratypes.— 48 specimens, 11.1–27.9 mm SL. Indonesia: USNM 211918 , ca. 16 mm SL, west of Kasa Island , Maluku, 03818 0 S, 128808 0 E, 1.2 m, V. Springer, 4 March 1974 ; USNM 211939 , 22.5 mm SL, Naira Island, Banda islands , Maluku, 04820 0 30 00 S, 129854 0 20 00 E, 3–9 m, V. Springer et al., 8 March 1974 ; WAM P. 35182-001, 2, 20.7–21.4 mm SL, Ampera, Alor, Lesser Sundas , 8816 0 04 00 S, 124825 0 31 00 E, 5 m, M. Erdmann, 4 May 2019 . Malaysia: KPM-NI. 1982, 24.5 mm SL, KPM-NI. 1983, 18.5 mm SL, YCM-P 36726 , 2 , 19.7–20.5 mm SL, YCMP 36727 , 11.5 mm SL, YCM-P 37150 , ca. 19.0 mm SL, Mabul Island, Sabah. Palau: BPBM 9219 , 27.9 mm SL, Arakabesang Island , 0.6–0.9 m, J. Randall and E. Helfman, 5 June 1968 ; CAS 247204 , 25.1 mm SL, Melekeok, Babelthuap Island , 07821 0 04 00 N, 134831 0 23 00 E, 1.2 m, Y. Sumang and H. Fehlmann, 23 June 1958 . Philippines: FMNH 127786 , 19 (2 of 19 CS), 12.5–26.5 mm SL, north of Cabilauan Island , Palawan, 12812 0 32 00 N, 120807 0 49 00 E, Busuanga Team, 5 March 2003 ; KAUM-I. 146168, 20.9 mm SL, KAUM-I. 146169, 18.2 mm SL, KAUM-I. 146170, 17.1 mm SL, USNM 451066 (formerly USNM 360264 ), 5, 15.0– 23.1 mm SL, same as holotype ; ROM 55178 , 11.6 mm SL, Pasihagon, Siquijor Island , Siquijor, 09812 0 17 00 N, 123827 0 16 00 E, 10.4 m, R. Winterbottom and E. Downar, 10 May 1987 , rotenone; ROM 55181 , 11.1 mm SL, Pasihagon, Siquijor Island , Siquijor, 0981201600 N, 123827 0 16 00 E, 10.3 m, R. Winterbottom et al., 12 May 1987 , rotenone; ROM 55183 , 19.2 mm SL, Pasihagon, Siquijor Island , Siquijor, 09812 0 16 00 N, 123827 0 16 00 E, 18.8 m, R. Mooi et al., 14 May 1987 , rotenone; ROM 55185 , 4 (1 of 4 CS), 11.5– 23.8 mm SL, mouth of North Basis Bay, Negros Island , Negros Oriental, 09837 0 00 00 N, 123810 0 00 00 E, 23.1 m, R. Winterbottom et al., 17 May 1987 , rotenone; USNM 360265 , 2 , 12.4–13.3 mm SL, San Juan, Siquijor Island , Siquijor, 09808 0 30 00 N, 123829 0 22 00 E, 6.1 m, Smithsonian Team, 9 May 1978 . Sri Lanka: USNM 360162 , 22.9 mm SL, Trincomalee , 7.6 m, C. Koenig, 4 April 1970 .

Diagnosis.— A species of Flabellicauda ( Figs. 3 , 4A–E , 5 ) distinguished from congeners by the following combination of characters: 12–15 (modally 13) dorsal-fin rays (vs. 11 or 12 in F. akiko ; 10–12 in F. cometes , new species; Table 2); 10–13 (11, rarely 10) anal-fin rays (vs. 9 or 10 in F. akiko ; 9–11 in F. cometes , new species; Table 2); upper end of gill opening level with base of 12 th to 14 th pectoral-fin ray in lateral view (vs. 9 th or 10 th in F. akiko ); 5–8 (6, rarely 5), 6–8 (6), and 6–8 (7) gill rakers on first to third arches, respectively (vs. 4, 4 or 5, and 5, respectively in F. akiko ; 4–6 [5], respectively in F. bolini ; 5, 5, and no data, respectively in F. cometes , new species; Table 3); head sensory canal pores relatively developed, including usually 2 nasal, 2 lacrimal, and 2 postorbital pores (vs. lacking lacrimal pores and 1 postorbital pore present in F. akiko and F. cometes , new species; 1 nasal pore present in F. akiko ; Fig. 6 ); disc region A without papillae at center (vs. disc region A with papillae at center in F. akiko ; Fig. 7A, D ); body black with white stripes (vs. body red with white stripes in F. akiko ; Figs. 5 , 8F–H ). Flabellicauda alleni is most similar to F. bolini and in addition to the aforementioned diagnostic characters, values of head length, pre-disc length, orbit diameter, and caudal-peduncle length and width proportions also serve to distinguish between the two species (see Diagnosis of F. bolini ).

Description.— Measurements given in Table 4. Body slender, cylindrical, compressed at caudal peduncle. Body width narrower than head width. Anus situated closer to anal-fin origin than to posterior margin of disc (disc to anus length 69.4 [62.7–78.3, mean 69.2] % of disc to anal-fin origin length). Head size medium, becoming smaller with growth ( Fig. 9A ), depressed anteriorly, its length and width 3.5 (2.7– 3.5 [mean 3.1]) and 5.5 (5.1–7.2 [6.2]) in SL, respectively. Snout moderate, its length 12.7 (9.2–13.1 [11.3]) in SL, becoming shorter with growth ( Fig. 9E ), its tip slightly pointed in lateral view, semi-elliptical (or duck beak-shaped) in dorsal view; dorsal profile of snout slightly concave anteriorly. Mouth terminal, small, restricted to tip of snout. Anterior tip of upper jaw slightly pointed, extending slightly beyond that of lower jaw. Upper lip fleshy, weakly expanded, lower lip thin. Posterior 2/3 of both jaws covered by thick skin on lateral surface of snout. Anterior and posterior nostrils larger than head sensory canal pores, former slightly smaller than latter; both with a membranous tube, that of former much longer than latter. Eye size moderate, becoming smaller with growth ( Fig. 9D ), diameter slightly smaller (slightly larger in 9 specimens) than snout length, 14.6 (8.8–15.6 [12.3]) in SL. Interorbital region flattened. Gill opening tiny, slit-like. Upper end of gill opening level with base of 12 th (12 th to 14 th) pectoral-fin ray in lateral view (number of pectoral-fin rays given in Table 2); lower 9 th (7 th [6 specimens], 8 th [20], or 9 th [12]) pectoral-fin-ray base attached to disc by membrane. First to third gill arches with two rows of gill filaments, 4 th arch without filaments (gill description based on 21 specimens). Gill rakers slender, short and pointed (gill raker counts listed in Table 3). Gill membranes on each side united ventrally, attached to isthmus. Head sensory canal pores relatively developed, including 2 nasal, 2 (1 on left side only in 2 specimens; 1 on both sides of 1 specimen) lacrimal, and 2 (1 on both sides of 2 specimens) postorbital pores; preopercular and mandibular pores absent; all pores similarly sized with minute membranous tube. NC1 located in front of anterior nostrils in dorsal view (or between anterior and posterior margins of anterior nostril); NC2 level with anterior margin (before anterior margin [7 of 41 specimens], between anterior and posterior margins [24 specimens], or level with posterior margin [2 specimens]) of posterior nostril; LC1 located in front of anterior margin of eye; LC2 located postero-ventrally below LC1 (antero-ventrally below LC1 [3 of 37 specimens] or just below LC1 [7 specimens]); PO1 located just behind posterior margin of orbit; PO2 located posterodorsal to PO1 ( Fig. 6A–C ).

Dorsal- and anal-fin-ray counts listed in Table 2. Origin of dorsal fin slightly anterior to vertical through anal-fin origin. Dorsal and anal fins located posteriorly, their bases relatively long, lengths 4.6 (4.4–6.4 [5.1]) and 5.4 (4.9–6.9 [5.7]) in SL, respectively; strongly connected to caudal fin by membranes, giving appearance of single, continuous median fin around posterior part of body (easily damaged). Post-dorsal-caudal length 4.9 (3.5–7.0 [5.1]) in dorsal-fin base length. Dorsal- and anal-fin heights almost equal, except anteriorly. Pectoral- and caudal-fin margins rounded. Pectoral-fin rays 28 (26 [5], 27 [8], 28 [13], 29 [11], or 30 [1]). Upper and lowermost pectoral-fin rays minute, longest ray extending beyond vertical through posterior margin of disc. All soft-fin rays unbranched and segmented. Pelvic fins and pectoral-girdle elements forming a circular, extremely small, ‘‘single’’ adhesive disc ( Fig. 7A ), its length and width 9.6 (7.4–12.4 [9.7]) and 9.3 (7.9–13.4 [10.0]) in SL, respectively. Disc region B bell-shaped, equal in size to disc region A. Anterior margin of disc region A smooth, posterior margin of disc region B with fringe. Disc regions A and B with flattened papillae (disc papillae description based on 33 specimens). Center of disc region A lacking papillae; anterolateral part with 3 (3–5) rows of papillae, number of rows slightly decreasing toward apapillate center; both sides of disc region A (except margins) covered with papillae; papillae of inner rows slightly larger than papillae of outer rows. Disc region B with 5 (4–6) rows of papillae; papillae of inner rows slightly larger than papillae of outer rows; anterior part of disc region B without papillae ( Fig. 7A ). Disc region C lacking papillae.

Osteological description based on 3 CS specimens and CT-scanned image ( Fig. 10 ). General osteological characters as in Figures 2A , 10–13 . Vertebrae 34 (1 specimen) or 35 (3). Neurocranium depressed, comprising nasal, lacrimal, lateral ethmoid, mesethmoid, sphenotic, pterotic, epiotic, prootic, supraoccipital, basioccipital, exoccipital, frontal, vomer, parasphenoid, and parietal ( Fig. 11 ). Posterior tip of epiotic articulating with posttemporal; sphenotic and pterotic contributing to hyomandibular facet accommodating articular heads of hyomandibular; lacrimal firmly attached to tip of slender cartilage extending from anterolateral tip of lateral ethmoid. Antero-center point of vomer slightly protracted; posterior tip of vomer pointed in ventral view. Anterior tip of nasal slightly forked, tapering posteriorly; its posterior tip articulating with anterior part of frontal; middle portion of nasal with sharp lateral process at exit of nasal canal. Jaws comprising maxilla, premaxilla, dentary, anguloarticular, and retroarticular ( Fig. 12 ). Premaxilla with laterally compressed incisiviform teeth with hook-like tip, strongly curved posteriorly (ca. 908). Ascending process of premaxilla long, terminating slightly posterior to imaginary line through posterior tip of nasal; premaxillae separated anteriorly by large circular gap in dorsal view. Maxilla irregular, boot-shaped, with elongate part oriented along dorsal-ventral axis; connected with premaxilla via well-developed, bifurcated articular head. Anterior half of dentary with pointed conical teeth, inner surface slightly curved; posteromedial face of dentary with squarish process. Anterior ca. 1/3 part of anguloarticular pointed, articulating with dentary; coronoid process of anguloarticular well developed, tip rounded, directed anterodorsal. Retroarticular tiny, elongate, nestled in articular facet located on posteroventral part of anguloarticular. Suspensorium comprising autopalatine, quadrate, hyomandibular, ectopterygoid, and symplectic ( Fig. 12A ). Autopalatine a curved cylinder, articulating with lateral ethmoid dorsally, and premaxilla and maxilla anteriorly. Ectopterygoid triangular, its lower margin strongly connected with quadrate via elongate suture. Symplectic a slender rod, articulating with posterior triangular part of quadrate anteriorly and anteroventral part of hyomandibular posteriorly. Opercular bones comprising opercle, subopercle, preopercle, and interopercle; all bones poorly ossified, excluding articular head of opercle; subopercle without spine-like posterior tip ( Fig. 12A ). Gill arches comprising basihyal, 4 paired epibranchials, paired pharyngobranchial 3 and associated tooth plate, 3 paired hypobranchial elements (bone or cartilage), 5 paired ceratobranchials, and 3 basibranchial elements (bone or cartilage; Fig. 12D ). Basihyal long, slender, anterior tip cartilaginous. Pharyngobranchial 3 flat, irregularly shaped with anteromedial and posteromedial cartilaginous process, articulating with cartilaginous head of epibranchial 2 and 3, respectively. Pharyngobranchial 3 tooth plate associated (fused) with ventral surface of pharyngobranchial 3, with 2 rows of 3–4 conical teeth on ventral surface. Hypobranchial 1 and 3 thin, perichondrally ossified bone around precursor hypobranchial cartilages 1 and 3, respectively; hypobranchial 2 cartilage without associated ossification. Ceratobranchial 5 tiny, without pharyngeal teeth. Three basibranchial elements situated between second and third hypobranchial elements and tip of ceratobranchial 4; basibranchial 3 a thin, pericondrially ossified bone around precursor basibranchial 3 cartilage; basibranchial 2 and 4 cartilages without associated ossification; basibranchial 1 cartilage absent. Hyoid bar comprising dorsal hypohyal, anterior and posterior ceratohyal, interhyal, and 6 branchiostegal rays ( Fig. 12E ). Anterior ceratohyal tightly connected with dorsal hypohyal anterodorsally; separated from posterior ceratohyal posteriorly by thin band of cartilage. Interhyal well developed, similar in size to posterior ceratohyal. Urohyal deeply forked posteriorly. Dorsal hypohyal elongate, similar length as urohyal. Pelvic- and pectoral-fin girdles comprising basipterygium, dorsal postcleithrum, ventral postcleithrum, posttemporal, supracleithrum, cleithrum, scapula, coracoid, and 4 pectoral radials ( Fig. 13 ). Anterior outline of basipterygia together triangular, posterior outline resembles inverted T-shape. Anteromedial tip and lateral edge of basipterygium cartilaginous; two large oval openings at center. Dorsal postcleithrum oblong shape, with well-developed fimbriae along posterior edge. Ventral postcleithrum irregular in shape; anterior margin with 2 pointed processes, outer process much larger than inner process; posterior margin concave, with well-developed fimbriae. Complex articulation present between posterior tip of basipterygium and anteromedial edge of ventral postcleithrum. Pelvic-fin rays I, 4, articulating with cartilaginous lateral edge of basipterygium; pelvic spine short, tip wide, rounded; soft rays slender, tapering distally ( Fig. 13C ). Four pectoral radials (1–4) with cartilaginous posterior tip; bony struts along ventral (pectoral radial 1), dorsal (pectoral radial 4), or both ventral and dorsal margins (pectoral radials 2 and 3) interdigitating with struts borne on element(s) directly above and/or below ( Fig. 13E ). Scapula irregular in shape, tightly connected with dorsal surface of pectoral radial 1 ( Fig. 13E ). Coracoid bifurcated anteriorly, pointed posteriorly; tightly connected with ventral surface of pectoral radial 4 ( Fig. 13E ). Caudal skeleton comprising single hypural plate, epural, and parhypural ( Fig. 2A ). Upper and lower hypural plates fused, forming large fan-shaped plate; small circular opening, potential remnant of diastema between upper and lower hypural plate in other gobiesocids, at center of hypural plate; 13 (2 specimens) or 14 (2) caudal-fin rays associated with plate. Epural and parhypural thin, perichondrally ossified bone around triangular precursor cartilages.

Coloration.— Based on Figures 3 , 4A–E , 5 , 8A–D . Body black with white stripe on dorsal midline ( Fig. 5C ) and three white stripes on each side ( Fig. 5A, B, D ); uppermost stripe extending from snout tip, past dorsal margin of pupil and pectoral fin, to caudal-fin base, its width very narrow on snout, gradually wider from head region, widest on body, slightly tapering posteriorly; central stripe narrowest of three stripes, extending from posterior point of lower jaw (or snout tip; Fig. 5A ), passing below pupil, to pectoral-fin base, both tips tapering; lowermost stripe located ventrally, united in front of pelvic disc, forming large isosceles triangle shape, its tip located on ventral surface of snout tip ( Fig. 5E ), posterior tip of stripe tapering and reaching caudal-fin base, its width on body same as uppermost stripe; stripe on dorsal midline tapering posteriorly and extending from snout tip to dorsal-fin origin; all stripes edged very faint yellow (sometimes distinct in life; Fig. 8A–C ). Stripes of single individual from Philippines notably narrower than in other individuals ( Fig. 8D ). Iris black except for upper and lower portions, pupil black. Tubes of nostrils and all fins except for rays transparent, fin rays faint black. Adhesive disc white, isosceles triangle shape of black pigmentation at center, its tip located at anterior margin of disc ( Fig. 5E ).

Preserved coloration uniformly yellowish ( Fig. 3 ). Black melanophores present on body of small specimens (ca., 20 mm SL), those forming two stripes (somewhat indistinct in large specimens; Fig. 4A, B ), upper and lower stripes located dorsally and laterally, respectively, former extending from nape to most posterior point of dorsal-fin base, latter extending from pectoral-fin base to caudal-fin base ( Fig. 4A–E ).

Distribution.— Known from Sri Lanka and Southeast Asia ( Philippines, Palau, Malaysia, and Indonesia; Fig. 14 ).

Etymology.— Named for Dr. Gerald R. Allen (WAM), for his great contributions to the systematics of tropical reef fishes of the East Indies. A noun in the genitive.

Figures

FIG. 1. Lateral view of heads of (A) Flabellicauda alleni, new species, WAM P. 35182-001, preserved specimen, 21.4 mm SL; (B) Lepadichthys frenatus, AMS I. 20256-013, preserved specimen, 35.3 mm SL; (C) Diademichthys lineatus, KAUM-I. 79654, 26.4 mm SL; (D) Discotrema crinophilum, KAUM-I. 72122, 26.3 mm SL; (E) Lepadichthys lineatus, KAUM-I. 128500, 22.0 mm SL; (F) Lepadichthys minor, KAUM-I. 70995, 18.2 mm SL; (G) Lepadichthys trishula, KAUM-I. 71567, 31.1 mm SL; and (H) Lepadicyathus mendeleevi, ZIN 53413, preserved holotype, 13.5 mm SL.

FIG. 2. Caudal skeletons of (A) Flabellicauda alleni, new species, FMNH 127786, 17.1 mm SL; (B) Flabellicauda cometes, new species, ROM 55928, 10.3 mm SL; (C) Lepadichthys frenatus, AMS I. 27134-018, 30.3 mm SL; (D) Lepadichthys minor, ROM 73449, 13.4 mm SL; (E) Discotrema crinophilum, ROM 85350, 25.4 mm SL; (F) Diademichthys lineatus, ROM 65282, 35.6 mm SL; (G) Gobiesox funebris, AMNH 5557, 46.7 mm SL; and (H) Acyrtus rubiginosus, UF 149202, 20.0 mm SL. Scale bars ¼ 1 mm. Abbreviations: AFR, anal-fin ray; DFR, dorsal-fin ray; DRC, cartilaginous distal radial; Ep, epural; EpC, epural cartilage; HP, hypural plate; HSPU2, hemal spine of preural centrum 2; LHP, lower hypural plate; NSPU2, neural spine of preural centrum 2; Ph, parhypural; PhC, parhypural cartilage; P-MR, proximalmiddle radial; PU, preural centrum; UC, ural centrum; and UHP, upper hypural plate. Asterisks indicate diastema between UHP and LHP.

FIG. 3. Preserved specimens of Flabellicauda alleni, new species. (A–C) USNM 360264, holotype, 26.2 mm SL, Palawan, Philippines; (D) KPM-NI. 1982, 24.5 mm SL, Sabah, Malaysia; and (E) USNM 360162, 22.9 mm SL, Trincomalee, Sri Lanka. (A, D, E) Lateral views. (B) Dorsal view. (C) Ventral view.

FIG. 4. Preserved small specimens of (A–E) Flabellicauda alleni, new species, and (F–J) Flabellicauda bolini. (A, B) YCM-P 36726, 19.7 mm SL, Sabah, Malaysia; (C–E) YCM-P 36727, 11.5 mm SL, Sabah, Malaysia; (F, G) CAS 224422, 16.2 mm SL, Suva, Fiji; and (H–J) CAS 224419, 13.2 mm SL, Vanua Levu Island, Fiji. (A, C, F, H) Lateral views. (B, D, G, I) Dorsal views. (E, J) Ventral views.

FIG. 5. Fresh coloration of Flabellicauda alleni, new species. (A) KPM-NI. 1983, 18.5 mm SL, Sabah, Malaysia (image reversed); (B, C) KPM-NI. 1982, 24.5 mm SL, Sabah, Malaysia (image reversed); and (D, E) WAM P. 35182-001, 21.4 mm SL, Lesser Sundas, Indonesia. (A, B, D) Lateral views. (C) Dorsal view. (E) Ventral view. (A–C) Photos by H. Senou.

FIG. 6. Head sensory canal pores of (A–C) Flabellicauda alleni, new species, and (D–F) Flabellicauda cometes, new species. Illustrations based on (A–C) USNM 360264, holotype, 26.2 mm SL and (D–F) ROM 55929, holotype, 17.3 mm SL. (A, D) Dorsal views. (B, E) Lateral views. (C, F) Ventral views. Scale bars ¼ 1 mm. Abbreviations: AN and PN, anterior and posterior nostrils, respectively; LC, lacrimal canal pores; NC, nasal canal pores; PO, postorbital canal pores.

FIG. 7. Pelvic discs of (A) F. alleni, new species, USNM 360264, holotype, 26.2 mm SL; (B) F. cometes, new species, ROM 55929, holotype, 17.3 mm SL; (C) F. bolini, ANSP 128248, 20.6 mm SL; and (D) F. akiko, WAM P. 33772-002, 11.5 mm SL. Scale bars ¼ 0.5 mm. Black dots indicate lacking disc papillae patch.

FIG. 8. Underwater photographs of (A–D) F. alleni, new species, (E) F. bolini, and (F–H) F. akiko. (A–C) 1.5 m depth, Rinca Island, West Flores, Indonesia. Photos by M. Erdmann. (D) 7 m depth, Bohol, Philippines. Photo by K. Yamasaki. (E) 5 m depth, Manus, Papua New Guinea. Photo by G. Allen. (F) 70 m depth, West Papua, Indonesia. Holotype. Photo by G. Allen. (G) 70 m depth, West Papua, Indonesia. Photo by M. Erdmann. (H) 40 m depth, Okinawa Island, Japan. Photo by N. Shirakawa. (A–E, G, H) Specimens not collected. (E, F) Reproduced from Allen and Erdmann (2012) with permission.

FIG. 9. Relationships of (A) head length, (B) pre-disc length, (C) head length plus pre-disc length, (D) orbit diameter, and (E) snout length (as % of standard length) to standard length (mm) in F. alleni, new species (red diamonds) and F. bolini (blue circles), showing (A–D) differences and (E) morphological change with growth.

FIG. 10. CT-scanned skeleton of Flabellicauda alleni, new species, ROM 55185, 21.5 mm SL. (A) Lateral view of whole body. (B) Dorsal view of anterior body. (C) Lateral view of anterior body. (D) Ventral view of anterior body. Abbreviations: ACh, anterior ceratohyal; Ana, anguloarticular; Apa, autopalatine; Bh, basihyal; Bp, basipterygium; Br, branchiostegal rays; Cl, cleithrum; Cor, coracoid; De, dentary; DHh, dorsal hypohyal; DPcl, dorsal postcleithrum; EpC, epicentral; Ect, ectopterygoid; Epoc, epiotic; Exoc, exoccipital; Fr, frontal; HS, hemal spine of ventral postcleithrum; Hy, hyomandibular; I, pelvic-fin spine; Ih, interhyal; Iop, interopercle; La, lachrymal; LE, lateral ethmoid; M, mesethmoid; Mx, maxilla; Na, nasal; NS, neural spine of ventral postcleithrum; Op, opercle; Pa, parietal; PecR, pectoral radial; Pmx, premaxilla; Pop, preopercle; Psph, parasphenoid; Pt, posttemporal; Pte, pterotic; PU, preural centrum; Q, quadrate; Ra, retroarticular; Ri, rib; Sc, scapula; Scl, supracleithrum; Soc, supraoccipital; Sop, subopercle; Sph, sphenotic; Sym, symplectic; Ur, urohyal; V, vertebral centrum; Vo, vomer; and VPcl, ventral postcleithrum.

FIG. 11. Neurocranium of Flabellicauda alleni, new species, FMNH 127786, 16.5 mm SL. (A) Dorsal view. (B) Lateral view. (C) Ventral view. Scale bar ¼ 1 mm. Abbreviations: Boc, basioccipital; EC, epiphyseal commissure of supraorbital canal; OC, otic canal; Pro, prootic; and SC, supraorbital canal. Other abbreviations as in Figure 10. Asterisks indicate articular condyles that accommodate articular heads of hyomandibular on sphenotic and pterotic.

FIG. 12. Viscerocranium of Flabellicauda alleni, new species, FMNH 127786, 16.5 mm SL. (A) Hyopalatine arch and opercular series, right side in lateral view (image reversed); margins of opercular bones highlight- ed with thin black lines. (B) Lower jaw in lateral view. (C) Upper jaw in dorsal view. (D) Gill-arch elements in dorsal view; margins of ceratobranchial bones of right side highlighted with thin black lines. (E) Hyoid bar, right side in medial view and urohyal. Abbreviations: AsPr, ascending process of premaxilla; Bb, basibranchial; Cb, ceratobranchial; CoPr, coronoid process; Eb, epibranchial; GFC, gillfilament cartilage; GR, gill raker; Hb, hypobranchial; MC, Meckel’s cartilage; MPr, median process of dentary; PbTP3, pharyngobranchial 3 toothplate; PCh, posterior ceratohyal; and RT, replacement teeth. Other abbreviations as in Figure 10.

FIG. 13. Internal supporting skeleton of the paired-fin girdles of Flabellicauda alleni, new species, FMNH 127786, 16.5 mm SL. (A) Pelvic disc in ventral view. (B) Pelvic disc supporting skeleton, including elements of the pelvic and pectoral-fin girdle in dorsal view (anterior to top of page); postcleithra and pelvic-fin rays of the right side removed. (C) Pelvic-fin rays of right side in dorsal view (anterior to top of page). (D) Pectoral-fin girdle of right side in medial view (anterior to left). (E) Close-up of elements of the pectoral-fin endoskeleton articulating with pectoral-fin rays of the right side in medial view (anterior to left). Abbreviations: PecFR, pectoralfin ray; PelR, pelvic-fin soft ray; PRC, pelvic-radial cartilage. Other abbreviations as in Figure 10.

FIG. 14. Distributional map of species of Flabellicauda: F. alleni, new species (red diamonds), F. cometes, new species (yellow squares), F. bolini (blue circles), and F. akiko (green triangles). Closed and open symbols indicate records based on specimens examined in this study and published photographs, respectively. Arrowheads indicate type locality.

FIG. 15. Relationships of (A) caudal-peduncle length, (B) caudal-peduncle depth, (C) caudal-peduncle length plus caudal-peduncle depth, (D) head width, (E) anterior interorbital width, and (F) posterior interorbital width (as % of SL) in F. alleni, new species (red diamonds), F. cometes, new species (yellow squares), F. bolini (blue circles), and F. akiko (green triangles).